Generally, destination devices, such as mobile phones, to which Web pages to be distributed, may require different output conditions on a receivable Web page, such as description language used to describe a Web page, saving format of Web page component data such as image data configuring a Web page, total data size of a Web page that is a sum of data size of document part of the Web page and data size of component part of the Web page, and display size that is limited by a size of display device of a destination device.
For example, a simple Web page, that contains just a document without any special font attribute and with no accompanying image data, may meet all of the above mentioned output conditions.
Some of destination devices may be capable of interpreting Web pages with rich contents such as large number of images, movies, animations, advanced layouts such multiple columns, and so on. In general, users of destination devices with such a high capabilities expect to browse Web pages with rich contents. Accordingly, if it is allowed to distribute Web pages with rich contents, the Web pages can attract more users of high-spec destination devices.
However, it is impossible to prepare Web pages with rich contents that meet all possible output conditions that may be required by any destination device. Accordingly, when the same Web pages with rich contents are distributed to destination devices with different capabilities, some of the destination devices cannot display the Web pages with rich contents.
If different versions of same Web pages with rich contents are prepared to meet the output conditions of each of different types of destination devices, the above-mentioned problem is solved. However, the solution requires for hosts of Web pages to prepare a large number of different versions of the Web pages in accordance with number of different possible output conditions that may be required by any destination device, and it is a heavy burden of the hosts of Web pages.
In the above-explained situation, a Web page distribution system that automatically converts Web pages to make the Web pages meet output conditions required by destination devices of the Web pages is proposed. (See, for example, Patent Literature 1.) The Web page distribution system has a distribution sever and a relay sever. Hosts of Web pages with rich contents are required to register only the original version of their Web pages to the distribution server. When the relay server relays distributions of Web pages from the distribution server to destination devices of the Web pages, the relay server automatically converts the original version of Web pages to a converted version of Web pages that meet output conditions required by the destination devices.
In the conversion of Web pages at the relay server, conversions between description languages of the Web pages, for example, conversions of saving formats of Web page component data such as image data, conversions of total data sizes of the Web pages, namely sums of data size of document part and data size of component part of the Web pages, and conversions of display sizes of Web page components such as image are executed.
As one of the methods for converting total data sizes of Web pages, i.e. sums of data size of document part and data size of component part of the Web pages, for example, Patent Literature 1 proposes a method to reduce a total data size of Web page by dividing the Web page into plural small Web pages. According to the method, the divided Web pages can be distributed one by one to a destination device, and total data size of a Web page distributed to the destination device at the same time could be reduced. As another method for converting total data sizes of Web pages, for example, Patent Literature 2 proposes a method to reduce a total data size of Web page by executing image conversion processing to make a display size of Web page content (image) smaller, to degrade quality, such as number of colors, of Web page content (image), and so on.